Safety means for electric circuits



Sept. 22, 1931. H. .1 BLAKESLEE 1 1,824,115

SAFETY MEANS FOR ELECTRIC CIRCUITS Filed Oct. 21, 1929 Patented Sept. 22, 1931 UNITED STATES PATENT OFFICE HENRY J.'BLAKESLEE,' or mLBono, CONNECTICUT my. MEANS FOR ELECTRIC cmcurrs Continuation of application Serial No. 219,917, filed September 16, 1927. This application filed October 21,

1929. Serial No. 401,271.

V This invention relates to means for automatically opening, in case of accident to the load lines,'the supply lines of electric light,

,, heat and power circuits.

The object of this invention is to provide simple means which will instantly open the supply line of a circuit whenever the load line becomes broken, and will retain the supply line open until the break is repaired and the conditions in the load line are restored to normal.

' This object is attained by connecting a trip switch in the circuit of a motor which is connected to operate a switch in the supply line, and, arranging means subject to the relative conditions of voltage and current n the load line which will cause the trip switch to shift the circuit connections so that the motor will open the supply line switch whenever the load circuit is broken, and will retain the supply line open until the load line break is repaired and the trip switch is closed.

The invention is adaptable to circuits that are controlled by time switches, and-consequently it is described herein in connection therewith, although applicable to clrcults controlled by other means.

This application is a continuation of my application Serial No. 219,917, filed Sept. 16, 1927. i

Fig. 1 shows diagrammatically the connections of a time switch arrangement in working relation, that is, when the main switch is closed and the load circuit is in normal'condition.

Fig. 2 is a similar view showlng the ele-' ments with the load line broken, the main switch open and the motor circuit open so that while the time mechanism will run as usual the motor circuit will remain open and the motor will not turn the main switch until the trip switch of the safety means is again closed.

I The time piece 1 is a clock of a common type used in time switch installations and it has the usual adjustable trips 2 which during their rotations, according to the positions in which they are set, engage with a finger 3 that is connected with an escapement anchor 4. Aspring 5 is arranged to normally keep the end of the finger in the path of the trips. The ends of the escapement anchor are designed to engage the arms of an escape wheel 6 which may be rotated by a spring 7. As the finger is depressed by a trip and subsequently rises, the anchor allows the escape wheel to be turned 90, after the manner of common anchor escapements. The escape wheel is fastened on a spindle 8 on which are fastened a conducting disk 9 and two segmental conductors 10 and 11, which disk and segmental conductors comprise the clock controlled switching means. This disk and these segmental conductors may be electrically connected through the spindle or by a conductor 12 and the segments are arranged at.90 with relation to each other so that first one segmental conductor will make contact with its brush 13 and the other'segmental conductor will make contact with its brush 14 as these arts are turned by the rotary movements of t e escape wheel. The brush 15 is always in conducting engagement with the disk 9.

The double pole main switch 16 which completes and opens the supply lines 17, 18 is fastened to a spindle 19. F astened on this spindle is a sprocket wheel 20 which isconnected by a chain 21 with a sprocket pinion 22 on the shaft of a motor 23. Also fastened on and rotating with this spindle and the main switch there is a conducting disk 24 and segmental conductors 25 and 26. This disk and these segmental conductors may be electrically connected through the shaft or b a conductor 27, and they comprise the switch which is turned with the main switch by the motor. In this case the segmental conductors are arranged at 90 with relation to each other and to the segmental conductors of the clock controlled switch. A brush 28 bears on the disk 24, a brush 29 is adapted to engage segmental conductor 25, and a brush 30 is arranged to engage segmental conductor 26. The brushes 14 and 30 are electri 95 cally connected by a conductor 31 and the brushes 13 and 29 are electrically connected by a conductor 32. The brush 28 is electrically connected by a conductor 33 with one. termin'al'of the secondary of a transformer V '34 that is connected across the supply lines 7 17 and 18. The other terminal of the secondary' of this transformer is connected by a conductor 35 with a brush 86 of the motor. The other brush 37 of the motor is connected by a conductor 38 with a trip lever 39 which is normally held in position toclo'se the circuit between the motor and the disk 9 through the conductor'tO that is connected with the brush of the disk=9; This; lever isretained with this partofthe circuit closed by a latch 41 and a spring 42 A- "spring 43 is arranged to pull the trip lever,

and 4&5 encircling. cores 46 andtZ which are when the latch is lifted so as to open the circuit' between the brush 15 and the motor and close the circuit between the brush 13 andthe motor,Fig; 2, c I y For thepurpose of lifting thelatch and releasingtlie. trip lever, the apparatus illustrated has. abalanced solenoid with coils 4A connected to a rocker 48, the core 46 being adapted to engage thelatch. The coil 44: is

connected with the load side of the main switch so as to be responsive. to the" voltage therein, which may be affected by connecting the ends. ofthe coil iwith the terminals of the secondary of a transformer 49 which is connected across the line, and the coil is connected with the load line so asto be responsive to the current therein, which may be affected by connecting the ends of the coil 45 withtheterminals of the secondary ofatransformerb'O inseriesin the load line, 1 which load: l1ne is illustrated as. receiving "its. current from the transformer 51. With broken through any accident no CUIIBII GWlll the circuits in normal working condition the solenoid cores arebalanced as the effect of the current in each coil will: be the same. Should, however, the load circuit become flow through the @1145 but current will still 50-1 remain open until the break in the load circontinue' to flow through the coil l4.

V This eliminates the solenoid balance so that the core 46 will be projected and cause the latch to release the trip lever,.which will then close the motor circuit. The motor will thenoperate to openthe main switch, the.

turning of which will again openthe motor circuit. The main and motor circuits will cuit is' rep aired, the trip switch. lever is reengaged with the latch,,and the. current. in

the solenoid coils is again balanced.

I In normal use the safety elements may be placed on poles or in manholes or at substations for the purpose of automatically open.-

ingyand keeping open the supply circuit whenever any break occurs in the load cirfiQ.

cuit.v Thefmotor circuit is. closed bytwo switches, one, comprising the disk 9- and the segmentalconductors 10 and 11, illustrated as: operatedv from the clock, and the other comprising the disk s4 and segmental conductors 25 and 26, operated from the motor,

and the main switch in the supply line is thrown positively by the motor. I When the load circuit is open the clock can go on in-' definitely for under these conditions the motor circuit is open and the mainswitch remains open. The clock through the. connections. illustrated automatically causes the main switchfirst to close and then to open according to the engagement of the trips on the time: piece with the linger connected to the escapement anchor.

- The clock circuit starts the motor and the motor drivesthe main switch both to open and close the supply line, when the load cir-' cuit is in working condition. On the completion of. each movement. of the main sw tch the clock-motor, clrcult. is: opened.

The apparatus, as stated,.is illustrated dia; V

trical source, aload circuit connected to said secondary winding, an electromagneti cally actuated switch havingtwo windings, one winding. adapted tobe energizedwhen said primary is energized, the other winding.

adapted to be energized when current flows in said load circuit, and conductors connecting the electromagnetically operated switch with the motor and with an electrical source, whereby when the current in the load. circuit is interrupted the electromagnetic switch will act to so connect said conductors that the motor will cause-the main-switch to disconnect the primary coil of the transformer from the electrical source.

I 2, Safety means for electric circuits comprising a transformer having primary and secondary windings, a motor, a main switch mechanically connected and operated by the motor and adapted toconnect and dis- I connect said primary winding with an. electrical source, a load circuit connected to said secondary winding, an electromagnetically actuated switch having two windings, one windingbeing connected with the secondary of a transformer adapted to be connected across the primary circuit, the other winding being connected with the secondary of a transformer adapted to be connected in the secondary circuit, and conductors connecting said electromagnetically operated switch with the motor and with an electrical source,

whereby when the current in the load circuit I is interrupted the electromagnetically operf ated switch will act to so connect said conductors that the motor will cause the main switch to disconnect the primary coil of the transformer from the electrical source.

3. Safety means for electric circuits comprising a motor, a main switch mechanically connected to and operated by the motor and adapted to connect and disconnect an electrical source with a load circuit, an electromagnetically actuated switch having two windings, one winding having an electrical connection across the load side of the main switch, and the other windin having an electrical connection in series w1th the load circuit, and conductors connecting the electromagnetically operated switch with the motor and with an electrical source, whereby when the current in the load circuit is interrupted the electromagnetic switch will act to so connect said conductors that the motor will cause the main switch to disconnect the load circuit from the electrical source.

4. Safety means for electric circuits comprising a motor, a main switch mechanically connected to and operated by the motor and adapted to connect and disconnect an electrical source with a load circuit, an electromagnetically actuated switch having two windin s, one winding being connected with a trans ormer connected across the load side of the main switch, and the other winding connected with a transformer connected in series with the load circuit, and conductors connecting said electromagnetically operated switch with the motor and with an electrical source, whereby when the current in the load circuit is interrupted the electromagnetically operated switch will act to so connect said conductors that the motor will cause the main switch to disconnect the load circuit from the electrical source.

5. Safety means for electric circuits comprising a main switch connected between an electrical source and a load, a motor mechanically connected to and operating the main switch, switching means and means for operating the same for opening and closing the motor circuit and causing the motor to throw the main switch, a trip switch in the motor circuit, and normally closed, and means responsive to change from the normal relations of the voltage supplied to the load circuit and the current in the load circuit, for releasing the trip switch and allowing it to open the normal circuit and close a circuit through the motor which will cause the motor to open the main switch.

, 6. Safety means for electric circuits comprising a main switch connected between an electrical source and a load, a motor mechanically connected to andoperating the main switch, switchin means and means for operating the same %or openin and closin the motor circuit and causing t e motor to t row the main switch, a trip switch in the motor circuit, and normally closed, and a'balanced solenoid. responsive to change from the normal'relations of the voltage sup lied to the load circuit and the current in t e load circuit, for releasing the trip switch and allowing it to open the normal circuit and close a circuit through the motor which will cause the motor to open the main switch.

7. Safety means for electric circuits comprisingamain switch connected between a currentsource and a load, a motor for operating the main switch, switching means o erated with the main switch, auxiliary switc ing means and means for operating the same, conductors electrically connecting the second mentioned switching means with the first mentioned switching means and with the motor,-a trip switch, conductors connecting the trip switch with the second mentioned switching means and with the motor, and means electrically associated With'the load circuit for controlling the trip switch, whereby when the load circuit is closed the motor circuit will be closed through the trip switch and the motor circuit will be controlled by the second mentioned switching means, and when the load circuit is open the trip switch will close the motor circuit so that the motor will open the main switch.

8. Safety means for electric circuits comprising switching means and means for operating the same, a'main switch connected between a current source and a load, a motor for operating the .main switch, switching means operated with the main switch, conductors electrically connecting the first mentioned switching means with the second mentioned switching means and with the motor, a trip switch, conductors connecting the trip switch with the first mentioned switching means and with the motor, and a balanced solenoid associated with and controlled from the load circuit and controlling the trip switch, whereby when the load circuit is closed the solenoid is balanced and will retain the trip switch in normal position, and when the load circuit is opened the solenoid is unbalanced and the trip switch will shift andclose the motor circuit so that the motor will open the main switch. a

9.. Safety means for electric circuits comprising switching means and means for operating the same, a main switch connected between a source of current and a load, a motor for mechanically operating the main switch, switching means operated with the main switch, conductors electrically connecting the netic means electrically associated with the load circuit for controlling the trip switch, said means being responsive to change from 4; c y 7 7 ,7 1582x1 15 the vnormal relations of the voltage suppliedi tor'the loadcircuit ancl'the cnrrentin'said load; circuit and when the load. circuit. is; -open will cause: the trip switch tolcloseathe motor cir cuit so that the" motor :willopenftheTmain: switch;v l

10; Safety means forelectric circuits com-- prising amotor, a main switch mechanically operated by said. motor and adaptedto conf nect: and disconnect a loadcircuitto an:electrical: source switchingimeans associated with: 7 said motor for normally closingiandopening V 7 said main switch, switching; means also fiSSO-x ciated with said motor and responsive to r r75: change from thenormal'relationsofthevoltage supplied tothe. load circuit and the. cur-- rent inisaicl loadcircuihand' conductorsinten connecting. said switching means and said motor whereby when the current in the lead V 26 circuit is interrupted said switching. means willso'connect saidconductors that the motor will cause said main. switch toopen.

11. Safety means for: electric circuits comprising; a motor, a main switch mechanically I '5 operateclbysaid motor-and adapted to' connect and disconnecta load circuit to an electrical Sourcdswitching means-associatedwith V saidmotor fornormally closing: and. opening: said main switch, electromagnetic switching;

aw means also associated with-said motor and responsive to change. from thenormal relations of the Voltage. supplied to the load cir-; cuit andrthe current. in sa'idloa'dcircuit, and conductors interconnecting said: switching 35? means and: said: motor whereby when the cure rent in the load circuitis interrupted said" switching: means will so connect saidconduc'-= tors-2 that the motor willcause said main switch toopen. v 7 an; 12. Safety means for electric circuits-comprising a main switch connected between a sourc'e of current. and a load,.a motor for me chanically operating: the main switch, switching means operated with themain switch, '41.)? auxiliary switching: means, conductors. GlGC-r. trica-lly connecting said switching means, a trip switch, conductors connecting thewtrip: switch withsaid switching; means and with the motor,- and normally balanced electro 7 no: magnetic means electrically associatediwith the 7 load: circuit for r controlling the trip switch-,;said magnetic means being balanced when the load circuitis closed, andnunba'lanced' when the loadcircuit-is'open sothat 2 thetrip switch will close themotor circuit andthe'niotorwill open the'main switch".

' HENRY J. BLAKESLEE. 

